Concordant sea‐floor spreading rates obtained from geochronology, astrochronology and space geodesy

Abstract

Reversals of the Earth's magnetic field, allied to sea‐floor spreading, have left their imprint in the form of a magnetic tape recorder on the sea‐floor. It is demonstrated that the geomagnetic polarity time scale for the past few million years, derived utilizing (a) radiometric dates of magnetic field reversals trapped in subareal, igneous, rocks and (b) as derived from the Milankovitch forcing frequencies and their imprint in the sedimentary environment, are in good agreement. Further, sea‐floor spreading rates calculated from these results, are in substantial agreement with the rate of plate movement averaged over the last decade, as obtained by space geodetic measurements. Since the principles underlying these “dating” techniques are entirely different, it lends credence to the results obtained for sea‐floor spreading, arguably the most fundamental process in plate tectonics.